Lonsdale 9314679 A pair of marine geophysical surveys, on each margin of the Pacific-Antarctic East Pacific Rise, will establish how this rise lengthened by 2500 km during the Cenozoic, and how it produced major offsets which define the large-scale segmentation of the present spreading center. Existing data indicate that growth of the rise was by creation and capture of risecrest microplates, rifting of old oceanic lithosphere, and migration of triple junctions, so the project will include investigation of these processes. Principal survey tools will be a multibeam sonar, magnetometer, and single channel seismic profiler.
